People with type 1 diabetes and impaired awareness of hypoglycaemia have a delayed reaction to performing a glucose scan during hypoglycaemia: a prospective observational study

Residual C-peptide is associated with new and persistent impaired awareness of hypoglycaemia in type 1 diabetes

AIMS

To describe the change in impaired awareness of hypoglycaemia (IAH) over time and to identify factors associated with this change in the Dutch Type 1 Diabetes biomarkers cohort (NCT04977635).

METHODS

A prospective cohort of type 1 diabetes patients, with C-peptide <300 pmol/L, who had completed the Clarke questionnaire, to determine IAH status, at baseline and after 2 years. Changes in awareness status were defined and compares as follows: unchanged normal awareness (NAH) versus unchanged IAH, new IAH versus reversal of IAH. Multivariate logistic regression models were fitted using forward and backward stepwise selection using a 0.10 P-value cut-off, and stepwise backward selection using AIC criteria.

RESULTS

A total of 431 out of 611 participants were included. The baseline prevalence of IAH was 17 % and 20 % after 2 years. The incidence proportion of new IAH and reversal of IAH were, 9.5 % and 31 %, respectively. For every 2.7-fold increase in C-peptide, the odds of IAH decrease by 58 %. A 1-unit increase in BMI over the 2-year follow-up period is associated with a 5.27-fold increase in the odds of reversing IAH.

CONCLUSIONS

Higher C-peptide levels are protective against new IAH, and an increase in BMI over time is associated with the reversal of IAH.

Altered functional connectivity during hypoglycaemia in type 1 diabetes

Behavioural responses to hypoglycaemia require coordinated recruitment of broadly distributed networks of interacting brain regions. We investigated hypoglycaemia-related changes in brain connectivity in people without diabetes (ND) and with type 1 diabetes with normal (NAH) or impaired (IAH) hypoglycaemia awareness. Two-step hyperinsulinaemic hypoglycaemic clamps were performed in 14 ND, 15 NAH and 22 IAH participants. BOLD timeseries were acquired at euglycaemia (5.0 mmol/L) and hypoglycaemia (2.6 mmol/L), with symptom and counter-regulatory hormone measurements. We investigated hypoglycaemia-related connectivity changes using established seed regions for the default mode (DMN), salience (SN) and central executive (CEN) networks and regions whose activity is modulated by hypoglycaemia: the thalamus and right inferior frontal gyrus (RIFG). Hypoglycaemia-induced changes in the DMN, SN and CEN were evident in NAH (all p < 0.05), with no changes in ND or IAH. However, in IAH there was a reduction in connectivity between regions within the RIFG (p = 0.001), not evident in the ND or NAH groups. We conclude that hypoglycaemia induces coordinated recruitment of the DMN and SN in diabetes with preserved hypoglycaemia awareness which is absent in IAH and ND. Changes in connectivity in the RIFG, a region associated with attentional modulation, may be key in impaired hypoglycaemia awareness.